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Publication numberUS7032457 B1
Publication typeGrant
Application numberUS 10/669,436
Publication dateApr 25, 2006
Filing dateSep 25, 2003
Priority dateSep 27, 2002
Fee statusLapsed
Publication number10669436, 669436, US 7032457 B1, US 7032457B1, US-B1-7032457, US7032457 B1, US7032457B1
InventorsBenjamin F. Dorfman
Original AssigneeNanodynamics, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for dielectric sensors and smart skin for aircraft and space vehicles
US 7032457 B1
Abstract
A new family of multifunctional smart coatings based on diamond-like atomic-scale composite materials which can provide a real-time control of the surface stress distribution and potentially dangerous stress diagnostic for the most critical parts of flying vehicles. The coating is a silica-stabilized dielectric film, particularly, a diamond-like atomic-scale composite material.
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Claims(10)
1. A stress sensor comprising:
a first electrode;
at least one other electrode; and
a dielectric layer disposed in relation to the first and the at least one other electrode for the electrodes to supply an electric field (E) to the dielectric layer, wherein the dielectric layer comprises a diamond-like carbon film that exhibits a change in conductivity when exposed to an electric field (E) at a level above a critical electric field (E*), wherein the critical electric field (E*) of the diamond-like film shifts under an applied stress, and wherein the critical electric field (E*) comprises about 2×105 V/cm.
2. A stress sensor comprising:
a first electrode;
at least one other electrode; and
a dielectric layer disposed in relation to the first and the at least one other electrode for the electrodes to supply an electric field (E) to the dielectric layer, wherein the dielectric layer comprises a diamond-like carbon film that exhibits a change in conductivity when exposed to an electric field (E) at a level above a critical electric field (E*), wherein the critical electric field (E*) of the diamond-like film shifts under an applied stress, and wherein compressive forces on the diamond-like carbon film lowers the value of the critical electric field (E*) and wherein tensile forces on the diamond-like carbon film increases the value of the critical electric field (E*).
3. A stress sensor comprising:
a first electrode;
at least one other electrode; and
a dielectric layer disposed in relation to the first and the at least one other electrode for the electrodes to supply an electric field (E) to the dielectric layer, wherein the dielectric layer comprises a diamond-like carbon film that exhibits a change in conductivity when exposed to an electric field (E) at a level above a critical electric field (E*), wherein the critical electric field (E*) of the diamond-like film shifts under an applied stress, and wherein the diamond-like carbon film has a thickness and the electrodes are disposed laterally with respect to each other a distance no greater than the thickness of the diamond-like carbon film.
4. A stress sensor comprising:
a first electrode;
a plurality of other electrodes; and
a dielectric layer disposed in relation to the first and the at least one other electrode for the electrodes to supply an electric field (E) to the dielectric layer, wherein the dielectric layer comprises a diamond-like carbon film that exhibits a change in conductivity when exposed to an electric field (E) at a level above a critical electric field (E*), wherein the critical electric field (E*) of the diamond-like film shifts under an applied stress, and wherein the diamond-like carbon film is deposited onto a surface of a structure being measured for stress as a continuous layer to serve as a sensing layer for the plurality of the other electrodes.
5. A method for determining whether a particular level of stress has been applied to a structure using a stress sensor comprising:
a first electrode;
at least one other electrode; and
a dielectric layer disposed in relation to the first and the at least one other electrode for the electrodes to supply an electric field (E) to the dielectric layer, wherein the dielectric layer comprises a diamond-like carbon film that exhibits a change in conductivity when exposed to an electric field (E) at a level above a critical electric field (E*), wherein the critical electric field (E*) of the diamond-like film shifts under an applied stress,
the method comprising:
applying an electric field (E) with the first electrode and the at least one other electrode to the dielectric layer;
monitoring the conductivity of the dielectric layer; and
determining whether the particular level of stress has been applied to the structure based on a change in the conductivity of the dielectric layer.
6. The method of claim 5, comprising determining whether the particular level of stress has been applied based on a shift in the critical electric field (E*) of the dielectric layer resulting from the applied stress.
7. The method of claim 6, comprising applying an electric field (E) at a level less than the critical electric field (E*) and determining whether a particular compressive stress has been applied to the structure based on a change in the conductivity of the dielectric layer which results from a shift in the critical electric field (E*) of the dielectric layer as a result of the compressive stress.
8. The method of claim 7, comprising determining whether a particular compressive stress has been applied to the structure based on a change in conductivity of the dielectric layer which results from a shift in the critical electric field (E*) of the dielectric layer to that less than the electric field (E) applied.
9. The method of claim 6, comprising applying an electric field (E) at a level greater than the critical electric field (E*) and determining whether a particular tensile stress has been applied to the structure based on a change in the conductivity of the dielectric layer which results from a shift in the critical electric field (E*) of the dielectric layer as a result of the tensile stress.
10. The method of claim 9, comprising determining whether a particular tensile stress has been applied to the structure based on a change in conductivity of the dielectric layer which results from a shift in the critical electric field (E*) of the dielectric layer to that greater than the electric field (E) applied.
Description

This application claims priority on U.S. Provisional Application Ser. No. 60/414,198 filed on Sep. 27, 2002 entitled: METHOD AND APPARATUS FOR DIELECTRIC SENSORS AND SMART SKIN FOR AIRCRAFT AND SPACE VEHICLES.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Sensors for critical stress diagnostic in real time and smart skin especially for aircraft and space vehicles.

2. Description of the Related Art

U.S. Pat. No. 5,797,623 (Hubbard, Aug. 25, 1998) discloses the Smart skin sensor for real time side impact detection. However, no patents or applications are known for sensor or smart skin based on the proposed physical phenomena.

SUMMARY OF THE INVENTION

A new family of multifunctional smart coatings based on diamond-like atomic-scale composite (DL ASC) materials developed over the past decade. The coatings will provide a real-time control of the surface stress distribution and potentially dangerous stress diagnostic for the most critical parts of flying vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (Prior Art) shows typical dependence of current (Log I, A) through stabilized diamond-like dielectric vs. Applied electrical field, V/cm.

FIGS. 2 a, b, and c shows shift of critical electrical field under stress: compressive stress shifts the threshold to the lower values of applied fields, while tensile stress shifts this threshold in the direction of higher fields.

FIG. 3,a shows array on electrically conducting substrate:

FIG. 3,b shows array on dielectric substrate:

FIG. 3,c shows the array with lateral electrodes:

FIG. 4 shows one of possible geometry of the ray forming a smart skin for aircraft wing;

FIG. 5 shows a cross sectional view of the protective top layer, the conductive electrode layer, the smart skin dielectric layer, and the metal substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 1 (Prior Art) shows typical dependence of current (Log I, A) through stabilized diamond-like dielectric vs. Applied electrical field, V/cm. The sharp transition in four orders of magnitude of electrical resistivity from about 1013 Om.cm to about 109 Om.cm occurred at 2×105 V/cm. The plot was received using 1-micrometer thick stabilized diamond-like dielectric film deposited upon conducting substrate; the area of the top electrode 0.1 cm2.

Joint electron-structural phase transition (the static Jan-Teller effect) occurs in diamond-like stabilized carbon at critical electrical field. When electrical field exceeds some certain critical point, typically E*=2×105 V/cm, the local fine structure of diamond-like matrix suddenly changes. The mean distance between nucleus of carbon atoms in certain atomic groups decreases, and electronic structure of those groups changes as well, adjusting to a new atomic arrangement. Such a joint electron-structural phase transition results with a sharp jump-like reversible increase of electrical conductivity of diamond-like dielectric on 3 to 4 orders of magnitude (FIG. 1). Typically, electrical resistivity decreases from the initial value of 1011 or 1013 Om.cm to a higher conductance state of 108–109 Om.cm. In the high-conducting state the current virtually does not depend on electrical field, although slightly fluctuates. When the electrical field E decreased below critical value E*, diamond-like dielectric instantly returns to the initial state. It is important to point, that in spite of this conductivity jump, diamond-like carbon remains as dielectric solid up to essentially higher field about 5×106 V/cm to 2×107 V/cm.

This physical phenomena was previously known as “the static Jan-Teller effect” by the names of two physicists who theoretically predicted it (H. Jahn and E. Teller, 1937). Although static Jan-Teller effect is found in many crystals, usually it observed by certain particularities of optical spectra, ultrasonic waves propagation, or electronic paramagnetic resonance. Strong and sharp change of electrical conductivity first observed in diamond-like carbon is unusual or even unique phenomena, and it is due to specific combination of electronic and mechanical properties of this low-density diamond-like carbon structures.

FIG. 2 shows shift of critical electrical field under stress: compressive stress shifts the threshold to the lower values of applied fields, while tensile stress shifts this threshold in the direction of higher fields.

Under external pressure or stretching force, or under internal compressive or tensile stress, the critical field is slightly changes (FIG. 2). Although the change of critical field is only about 0.1E*IGPa, if some pre-critical field E<E* applied to diamond-like dielectric, the sharp increase of electrical conductivity in a few orders of magnitude would instantly occur if compressive stress exceeds some critical value. Inversely, if some post-critical field E>E* applied to diamond-like dielectric, the sharp change of electrical conductivity in a few orders of magnitude would instantly occur if the tensile stress exceeds some critical value.

In accordance with present invention, silica-stabilized dielectric film is used as sensitive material for detection and diagnostics of dangerous stress and its location in structures, such as aircraft. This sensitive material may be used in individual sensors, and as a basic sensitive material for sensor arrays for smart skin technology (FIG. 3 a,b,c).

FIGS. 3 a–c shows 3 different approaches for electrical connection of diamond-like dielectric sensors into array:

FIG. 3 a shows array on electrically conducting substrate:

1—diamondlike dielectric layer (sensitive material), 2—conducting substrate, 3, 4—top electrodes and connecting lines, 5—bus to substrate.

FIG. 3 b shows array on dielectric substrate: 1-diamondlike electric layer (sensitive material), 2-dielectric substrate, 3-top electrodes and connecting lines, 4, 5-address buses, 6-electrically conducting sub-layer.

FIG. 3 c shows the array with lateral electrodes: 1—diamondlike dielectric layer (sensitive material), 2—substrate (dielectric or conductor), 7, 8—lateral electrodes.

Typically, the electrical field is applied cross the sensitive film thickness, and said thickness is typically in the range from a few hundred nanometers to a few micrometers. Depending on electrical properties of diagnosing surface, the different array geometry and connection between individual sensors may be applied, as it shown on FIGS. 3 a and 3 b. Also, lateral arrangement of the electrodes may be used (FIG. 3 c). In the last case the distance between two electrodes of a sensor should not exceed the film thickness. The last technology is relatively expensive and can be used for precise control of certain critical elements of the structure or during testing supporting new design.

It can sense stress space distribution along the entire surface of the structure, such as internal and/or external surface of the aircraft wing, in real time i.e., fractions of a millisecond. The sensors may be deposited directly upon the wing surface. The electrodes may be deposited after the sensitive material layer using the same technology and equipment while introducing metals in diamond-like carbon matrix. Both dielectric and conducting materials possess exceptionally high adhesion, abrasion and chemical resistance, excellent smoothness and tribological properties, thus simultaneously providing protection and improving aerodynamic properties of the wings.

The sensors is simple to manufacture and deposit along the entire structure.

For “smart skin” application, the advantage of Jan-Teller transition is completely dielectric state of sensitive smart film: it allows using a continuous “smart skin” sensitive in any point where a dangerous stress occurred (FIG. 1). Indeed, the most critical for the structure integrity is the tensile strength, while it would be easier to detect a compressive stress spot. This is because a compressive stress would produce the current increase in 2 to 4 orders of magnitude or higher, and a spot occupying about 0.01 of the entire area under electrode would be easily detected. However, any local increase of tensile stress in the integral structural body is accompanied with the compressive stress that will be detected. Thus, it would especially effective to integrate in smart skin both kinds of sensors: under pre-transition electrical field diagnosing compressive stress, and under post-transition electrical field diagnosing tensile critical stress. The intelligent electronic system would calculate the entire map of stress and location of a tensile stress spot in proximity of the initially detected compressed one.

Furthermore, the absolute value of the applied electrical voltage may be controllably varied through the sensor array, and the stress measurements, both compressive and tensile may be scanned along the entire smart skin in a reasonable proximity of critical value.

The coated body may be conductive or insulating. In the last case, a conducting sub-layer as a ground electrode (FIG. 3 b) should be deposited first, preferably the Me-C ASC deposited on the first step of the same continuous process. Top electrodes should be distributed over the sensitive dielectric layer and connected with the detector array, for instance along the trailing edge of aircraft wing. The network of top electrodes and connecting lines may be also deposited using Me-ASC. Finally, the whole parts of the vehicle, such as the wings, would be coated with a thin dielectric ASC to protect the sensitive smart skin and provide a uniform weather-resistant and aerodynamically sound coating for those parts.

FIG. 4 shows one of possible geometry of the array forming a smart skin for aircraft wing.

FIG. 5 shows a cross sectional view of the protective top layer, the conductive electrode layer, the smart skin dielectric layer, and the metal substrate.

A process for depositing the coating system may be shown in the following example:

1. The electrically conducting subject (FIG. 3 a, c) to be coated with smart skin, such as the aircraft wing (as shown on FIG. 4,5), is cleaned with a standard techniques of the vacuum industry.

2. The subject to be coated with smart skin is located in vacuum deposition chamber.

3. Air is pumped out of said deposition chamber up to about 1.0×10−5 Torr.

4. The chamber is filled with argon up to pressure of about 5×10−5 Torr, and the surface to be coated cleaned in the argon low pressure discharge during about 10 minutes.

5. Unalloyed stabilized diamond-like carbon 0.5 micrometer thick dielectric layer is deposited upon the surface of the structure (FIG. 3 a, c), such as the aircraft wing using a know techniques (such as those discussed in U.S. Pat. Nos. 5,355,2493, 5,718,976; and 6,080,470, each of which are hereby incorporated herein by reference). Said unalloyed stabilized diamond-like carbon dielectric layer possesses resistivity in an order of 1013 ohm.cm.

6. Chromium-alloyed diamond-like Me-C 1-micrometer thick conducting layer (as it shown in cross-section on FIG. 5) deposited upon said unalloyed stabilized diamond-like carbon dielectric layer; said chromium-alloyed diamond-like Me-C conducting layer possesses resistivity of about 10−4 Om.cm. Deposition of said unalloyed stabilized diamond-like carbon dielectric layer and said chromium-alloyed diamond-like Me-C conducting layer proceeded in the same vacuum chamber at the working pressure of about 10−5 Torr in one two-step continuous deposition process.

7. The chamber is filled with air up to atmospheric pressure and opened, the subject removed from chamber.

8. The patterning of electrodes and conducting lines (FIG. 3 a, 3, 4) realized with laser, such as CO2 laser, with a known technique.

9. The operations 2,3,4,5 repeated, and top dielectric layer deposited as a final protective layer of smart skin.

10. Operation 7 repeated.

11. The conducting lines connected with electronic control systems using standard technique known from the prior art.

The present invention, therefore, is well adopted to carry out the objects and attain the ends and advantages mentioned. While preferred embodiments of the present invention have been described for the purpose of disclosure, numerous other changes in the details of the material structure, composition, graded functionality and device designs can be carried out without departing from the spirit of the present invention which is intended to be limited only by the scope of the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US5352493May 3, 1991Oct 4, 1994Veniamin DorfmanMethod for forming diamond-like nanocomposite or doped-diamond-like nanocomposite films
US5466431May 25, 1994Nov 14, 1995Veniamin DorfmanDiamond-like metallic nanocomposites
US5718976Jun 7, 1995Feb 17, 1998Advanced Refractory Technologies, Inc.Erosion resistant diamond-like nanocomposite coatings for optical components
US5726524 *May 31, 1996Mar 10, 1998Minnesota Mining And Manufacturing CompanyField emission device having nanostructured emitters
US5797623Nov 3, 1995Aug 25, 1998Trustees Of Boston UniversitySmart skin sensor for real-time side impact detection and off-line diagnostics
US6071597 *Aug 28, 1997Jun 6, 20003M Innovative Properties CompanyFlexible circuits and carriers and process for manufacture
US6080470Jun 17, 1996Jun 27, 2000Dorfman; Benjamin F.Hard graphite-like material bonded by diamond-like framework
US6268161 *Sep 30, 1998Jul 31, 2001M-Biotech, Inc.Biosensor
US6469390 *Apr 21, 1999Oct 22, 2002Agere Systems Guardian Corp.Device comprising thermally stable, low dielectric constant material
US6835523 *Sep 15, 1999Dec 28, 2004Semiconductor Energy Laboratory Co., Ltd.Introducing an optical disk having a surface protected by a protective hard carbon film having thickness of 500 A or less, irradiating a semiconductor laser light on the disk through such hard carbon coating
US20030129497 *Sep 3, 2002Jul 10, 2003Nec CorporationElectrolytic cells; nonaqueous electrolytes, overcoating anode with amorphous carbon
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7938012Sep 12, 2007May 10, 2011Shaoxing Jinggong Equipment Monitoring Technology Co., Ltd.Smart coat for damage detection information, detecting device and damage detecting method using said coating
US8689644Mar 15, 2012Apr 8, 2014Airbus Operations S.A.S.Device for detecting shocks on a structure
US20100154556 *Dec 23, 2009Jun 24, 2010Huiming YinStrain Guage and Fracture Indicator Based on Composite Film Including Chain-Structured Magnetically Active Particles
EP2063243A1 *Sep 12, 2007May 27, 2009Shaoxing Jinggong Equipment Monitoring Technology Co., Ltd.Smart coating for damage detected information, inspecting device and damage inspecting method using said coating
EP2500706A1 *Mar 14, 2012Sep 19, 2012Airbus Operations (S.A.S.)Device for detecting impacts on a structure
WO2008043250A1 *Sep 12, 2007Apr 17, 2008Zhigang LvSmart coating for damage detected information, inspecting device and damage inspecting method using said coating
Classifications
U.S. Classification73/762, 73/769
International ClassificationG01B11/16
Cooperative ClassificationG01M9/06, G01M5/0016, G01L1/142, B64C3/26, B64C1/12, G01M5/0083, G01M5/0041
European ClassificationG01M9/06, B64C3/26, G01L1/14A, G01M5/00C, B64C1/12, G01M5/00N, G01M5/00R
Legal Events
DateCodeEventDescription
Jun 15, 2010FPExpired due to failure to pay maintenance fee
Effective date: 20100425
Apr 25, 2010LAPSLapse for failure to pay maintenance fees
Nov 30, 2009REMIMaintenance fee reminder mailed
Dec 24, 2008ASAssignment
Owner name: NANO-APPLICATIONS HOLDINGS B.V., NETHERLANDS
Free format text: SECURITY AGREEMENT;ASSIGNOR:NANODYNAMICS, INC.;REEL/FRAME:022024/0686
Effective date: 20081203
Owner name: NANO-APPLICATIONS HOLDINGS B.V.,NETHERLANDS
Free format text: SECURITY AGREEMENT;ASSIGNOR:NANODYNAMICS, INC.;US-ASSIGNMENT DATABASE UPDATED:20100203;REEL/FRAME:22024/686
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Oct 12, 2004ASAssignment
Owner name: NANODYNAMICS, INC., NEW YORK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DORFMAN, BENJAMIN;REEL/FRAME:015237/0118
Effective date: 20040712
Sep 23, 2004ASAssignment
Owner name: NANODYNAMICS, INC., NEW YORK
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ATOMIC SCALE DESIGN, INC.;REEL/FRAME:015169/0963
Effective date: 20040916
Sep 25, 2003ASAssignment
Owner name: ATOMIC-SCALE DESIGN, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DORFMAN, BENJAMIN F.;REEL/FRAME:014542/0624
Effective date: 20030924